Hi Steve, this article has the steps to make a backup copy of your entire profile: Back up and restore information in Firefox profiles.

One of the folders in the profile is sessionstore-backups. While Firefox is running, it frequently updates a file named recovery.jsonl4 in that folder. When you exit Firefox normally, Firefox removes that file and creates a new file named sessionstore.jsonlz4 at the main level of the profile folder (not in the sessionstore-backups subfolder). So at least one of those files should exist at any moment in time, containing a snapshot of the windows and tabs in your Firefox at the time it was created.

Normally, Firefox resumes your last session after an update, but if you are leaping over many versions, it sometimes may suggest doing a Refresh to improve performance. A Refresh moves your profile folder to your desktop inside a folder named Old Firefox Data. Firefox still should retain key data like bookmarks and open tabs after the update.

Thanks, I just copied the old profile as well as the session backup to a separate location. One thing you might want to mention doing would be to clear the cache before copying the profile to save disk space. In my case that is about 400Mb of useless junk.

Oh, sorry, I'm not sure how you ended up copying cache. You don't need to copy the folders under

C:\Users\username\AppData\Local\Mozilla\Firefox

at all. Firefox will rebuild fresh temporary folders for you. All the important stuff is under

C:\Users\username\AppData\Roaming\Mozilla\Firefox

You can set Windows to show hidden files and folders to make it easier to navigate and confirm paths: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files

So the profile is now split into two pieces?

The LOCAL folder profile seems to have the cache in it and it apparently was wiped during the update.

The ROAMING profile appears to have all of the other "stuff" in it. Good thing I happened to pick the correct one... purely by accident!

Saving user data INDEPENDENTLY (i.e. cookies, current browser state, bookmarks, etc) should be PARAMOUNT before any update takes place. This shouldn't be difficult. That way at least the data is there to recover when (NOT if) an update goes sour.

Any chance that you could pass this on to the Devs? They always claim that they want a GREAT browser EXPERIENCE. Nothing RUINS the browser experience as much as forever lost data and or work due to a borked update or other unforeseen issue..

Steve_Sr. said

The ROAMING profile appears to have all of the other "stuff" in it. Good thing I happened to pick the correct one... purely by accident!

Or by following the instructions in the article I linked to? That is why I couldn't understand why you were looking at a cache folder when making your backup. Where did that come from?

Saving user data INDEPENDENTLY (i.e. cookies, current browser state, bookmarks, etc) should be PARAMOUNT before any update takes place. This shouldn't be difficult. That way at least the data is there to recover when (NOT if) an update goes sour. Any chance that you could pass this on to the Devs?

Firefox users probably do a half million updates a month, and reports of lost data are rare, even on this support forum and Reddit where you would expect to get the most of them.

I don't know that anyone would feel it was worth automatically multiplying copies of user data files during every update without a clearer idea of the gain. Consider all the things that could go wrong in that process from disk space and permission issues to placing private data beyond the reach of ordinary cleanup features.

Perhaps Mozilla should arrange some backup offerings with one or more well-established and well-run cloud backup service providers. While some users are annoyed to see such things announced on the built-in home/new tab page, others might benefit considerably from getting into the habit.